Refrigerator apparatus including motor cooling means

ABSTRACT

The open drive motor for a refrigeration apparatus is mounted in a hermetic casing containing a quantity of a mixture consisting of a refrigerant and a lubricating oil. A passage extends from the upper portion of the casing to an auxiliary condenser, and a second passage returns condensed mixture to the motor casing. The auxiliary condenser is cooled by a metered flow of refrigerant from the condenser of the apparatus. The flow is metered to supply the condensed mixture in sufficient quantity to effectively cool the motor during continuous operation of the motor at full load.

United States Patent Endress REFRIGERATOR APPARATUS INCLUDING MOTORCOOLING MEANS [75] Inventor: James W. Endress, Syracuse, NY.

[73] Assignee: Carrier Corporation, Syracuse, NY.

[22] Filed: Oct. 29, 1973 [21] Appl. No.: 410,665

[52] US. Cl. 62/468, 62/505 [51] Int. Cl. F25b 31/00 [58] Field ofSearch 62/84, 468, 505

[56] References Cited UNITED STATES PATENTS 3,163,999 1/1965 Ditzler3,422,635 l/1969 Trenkowitz 3,563,051 2/1971 Brumgartner 62/468 Oct. 1,1974 Primary ExaminerMeyer Perlin Attorney, Agent, or FirmJ. RaymondCurtain 57 ABSTRACT The open drive motor for a refrigeration apparatusis mounted in a hermetic casing containing a quantity of a mixtureconsisting of a refrigerant and a lubricating oil. A passage extendsfrom the upper portion of the casing to an auxiliary condenser, and asecond passage returns condensed mixture to the motor casing. Theauxiliary condenser is cooled by a metered flow of refrigerant from thecondenser of the apparatus. The flow is metered to supply the condensedmixture in sufficient quantity to effectively cool the motor duringcontinuous operation of the motor at full load.

2 Claims, 1 Drawing Figure REFRIGERATOR APPARATUS INCLUDING MOTORCOOLING MEANS BACKGROUND OF THE INVENTION In certain refrigerationsystems the compressor is operated by an open drive motor. The opendrive motor is mounted externally of, and separate from, the compressor,as distinguished from an enclosed drive wherein the motor is mounted inthe compressor housing. The advantages of an open drive motor are wellknown, especially in that the motor can be quickly and convenientlyserviced and replaced if necessary. Also, if desired, the motor can bereplaced by a turbine or other primer mover. The advantage of arefrigerant cooled motor is also well known. The main advantage being inthat the rating of the motor may be reduced 25 percent or more. Thiseffects a saving of several thousand dollars in motor costs for a motordrive on large tonnage refrigeration apparatus.

Various arrangements have been proposed to cool open drive motors byrefrigeration. In one arrangement, there is provided an auxiliarycompressor and condenser. The refrigerant vapor is passed from the motorcasing to the inlet of the compressor and the liquid refrigerant isconveyed from the auxiliary condenser to the motor casing. In thatarrangement, a separate lubricating system is necessary to provide oilto the motor bearings. The motor bearings are sealed off to prevent theleakage of oil from the bearings into the refrigerant in the motorcasing. It is necessary to periodically inspect the seals to makecertain that the oil is not leaking into the refrigerant, especiallywhere the LII compressor is of the reciprocating piston type. Also, a

separate compressor has to be operated and maintained. In anotherarrangement, the refrigerant is passed directly from the mainrefrigerating apparatus to the motor casing. That arrangement has thesame disadvantage in regard to supplying the lubricant to the motorbearings.

SUMMARY OF THE INVENTION In this invention, the hermetically sealedmotor casing is provided with the supply of mixture containingrefrigerant and lubricating oil. A passage extends from the upperportion of the motor casing to the auxiliary condenser, and a passagefrom the condenser to the motor casing for the return of liquidrefrigerant. Means is provided for maintaining the refrigerant oilmixture in the motor casing at a selected level. There is a flowmetering means in a line extending from the main condenser to thecooling coil in the auxiliary condenser and is arranged to meter therefrigerant through the coil so as to maintain a flow of liquidrefrigerant and oil mixtures from the auxiliary condenser to the motorcasing sufficient to properly cool the motor when operated consistentlyunder full load.

BRIEF DESCRIPTION OF THE DRAWING The drawing discloses a schematic viewof a refrigeration system, the compressor of which is driven by a motorembodying my invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The refrigeration systemdisclosed in the drawing includes a centrifugal type compressor operableto draw refrigerant vapor from the cooler 11 through a passageway 12.The compressed vapor is discharged from the compressor through a line 13to a condenser 14.

The condenser is provided with a refrigerant sump containing a flowcontrol metering valve 21 for the discharge of liquid refrigerantthrough line 23 to the lower portion of the cooler 11. I

The motor for driving the compressor 10 includes a stator 25 and a rotor27. The rotor 27 is journaled for rotation in bearigs 30, 31 mounted inthe end walls 33-, 35 of the hermetically sealed casing 37.

A first passageway extends from the upper portion of the casing 37 to anauxiliary condenser 41. A heat exchanging coil 43 is mounted in thecondenser 4l.and is supplied with liquid refrigerant from the maincondenser 14 through a line 44 which includes a flow control device 45.Refrigerant is returned from the heat exchanger 43 to the cooler. Asshown in the drawing. the return line from the heat exchanger 43 isconnected in line 23.

Liquid refrigerant is conveyed from the auxiliary condenser 41 to themotor casing 37 by line 47. A supply of a mixture containing arefrigerant and a lubricating oil is maintained in the lower portion ofthe motor casing 37. The refrigerant vapor passing through the passage40 to the auxiliary condenser contains a quantity of the lubricating oilentrained therein. The refrigerant vapor is condensed in the condenser41 and returned through the passage 47, together with the oil entrainedin the vapor. The mixture is maintained at a predetermined levelindicated at by a metering valve 51 operated by a float 52. The valve 51is mounted in a chamber 53.

A pump 55 driven by a motor 56 operates to pump the mixture from themotor casing 37 through a line 57 for discharge onto the bearing 30 andagainst the confronting end of the rotor 27. The mixture is also pumpedthrough line 60 to the bearing 31 and to the shaft seal 62.

Inasmuch as the auxiliary condenser 41 is cooled with refrigerant fromthe main condenser 14, the mixture flowing through the return passage 47to the motor casing is at an exceptionally low temperature. The motor iscooled to a temperature substantially equal to the temperature in thecooler 11. This results in maintaining the oil in the mixture at highviscosity to provide good lubrication. This arrangement has theadvantage of permitting the use of a refrigerant in the mixturedifferent from the refrigerant in the refrigeration apparatus.

The meter device 45 may be in the form of a fixed orifice or anadjustable valve. In any event, the flow through the return passage 47is such as to'provide proper cooling of the motor when operatedconsistently at full load. Employing refrigerants conventionally usedand conventional types of lubricating oils, the mixture may consist of40 50 percent oil and 50. 60 percent refrigerant.

While I have described the preferred embodiments of my invention, it isto be understood that the invention is not limited thereto, but may beotherwise embodied within the scope of the following claims.

I claim:

1. A refrigeration system including a compressor, a condenser and acooler, a'motor operatively connected to the compressor for operatingthe same, said motor being mounted in a hermetically sealed'casing, aquantity of mixture of a refrigerant and a lubricating oil in the motorcasing, a passage extending from the upper portion of the motor casingto an auxiliary condenser and a second passage extending from theauxiliary condenser to the motor casing, means for maintaining saidmixture at a selected level in the motor casing, a heat exchanging coilmounted in said auxiliary condenser, a refrigerant line extending fromthe apparatus condenser to said heat exchanger and a return lineextending from the heat exchanger to the cooler of the apparatus, a flowmetering device in said line from said apparatus condenser to said heatexchanger and operable to meter a flow of refrigerant from the apparatuscondenser to said heat exchanger, said flow being sufficient toeffectively cool the motor operating under maximum load, a pump operableto circulate the mixture in said erant and 50 percent lubricating oil.

2. Apparatus as set forth in claim 1 wherein the mixture in said motorcasing consists of 50 percent refrigerant and 50 percent lubricatingoil.